Computer Telephony Integration (CTI) is a value added service for increasing voice transmission efficiency. Using CTI services, very simple applications such as computer-aided dialing, through to all call center functions can be offered as services. CTI basically involves using computer technology to support telephone services. This includes not only support of features with their various call processing functions but also the control and monitoring of PBXs and call detail recording.
A CTI platform generally includes fault tolerant servers and supports ITU Recommendations H.100 and H.110. Functional features usually include intelligent, network-oriented call control as well as automation of control and monitoring functions within a call center, software- and database-controlled functions for automatic call distribution and mechanisms for collecting and inserting stored and evaluated contact data.
Various manufacturer-developed CTI platforms standardized by various standardizing bodies have emerged over the years. There is therefore a plethora of more or less inter-related standards. CTI is based on the one hand on known standards such as ISDN and, on the other hand, defines hardware structure standards and interface standards. One such interface standard, for example, is CSTA (Computer Supported Telecommunications Application). CSTA specifies the structure and type of messages for various service features, such as hold toggling, call diversion, three-way conference.
With the existing methods of providing CTI services or features, only a port-related provision of CTI services is possible, but not a connection-related provision. This means that services or features can only be provided via ISDN B-channels at ISDN multi-terminal accesses, specifically ISDN S0 ports, if a connection (call) exists for each ISDN B-channel.